1. Field of the Invention
This invention relates to fat compositions which are particularly suitable for use as confectioners' butters and which are characterised by a randomised combined fatty acid composition conforming to specific requirements set out in more detail hereinafter.
The principal components of natural oils and fats are glycerides the fatty acids of which in combined form are found with different chain lengths and degrees of unsaturation. Different fatty acids may be found in the same glyceride molecule and in most natural fats a wide variety of glycerides is commonly found.
The nature of the fatty acids found in a fat and their distribution in the glycerides of which it is composed influences its melting characteristics and hence largely determines its suitability for edible purpose, in food products based essentially on fat compositions.
The melting requirements of a fat composition and therefore the nature of the fatty acids it contains vary according to the nature of the food product it is intended for and attempts to meet these requirements are based upon a judicious selection of fats, several of which may be blended to meet a particular purpose and by the further manipulation of its fatty acid content through fractionation and other, more sophisticated techniques the purpose of which is to concentrate those glycerides which are desired at the expense of those which are regarded as less desirable.
Although the melting characteristics of a fatty acid correspondingly affects those of a glyceride in which it is combined, with the result that a high melting fatty acid can form a high melting glyceride, the relationship is complicated in natural fats by the presence of a variety of fatty acids in several glyceride species and, combined within each glyceride molecule the possibility of more than one fatty acid. The melting point of fatty acid itself is influenced chiefly by its chain length and degree of unsaturation, naturally occurring unsaturated fatty acids being liquid at ambient temperatures, although it will be apparent that glycerides in which they occur may nevertheless be solid, owing to the greater influence of saturated, long chain fatty acids within the same glyceride molecule.
Although therefore some separation of combined fatty acids is effected by fractional crystallisation of fats, it is incomplete because high and low melting fatty acids may be combined within the same glyceride molecule.
The melting behaviour of a fat composition may also be modified by redistributing its fatty acids among the glyceride molecules of the fat. The overall fatty acid composition remains unchanged but the redistribution, which may be on a random or statistical basis throughout the glyceride molecules, substantially modifies the melting behaviour of the composition. Techniques have been developed in which the interesterification is constrained to favour the continued formation of a specified glyceride by continuously withdrawing it from the reaction, for example by fractional crystallisation. Reference may be made for further details of these techniques to Bailey's Industrial Oil and Fat Products, 3rd Edition (Interscience 1964). It is not within the ambit of this specifications to apply for protection of these fat manipulation techniques in themselves. The invention is concerned with the particular field of confectionery fats which are also known as confectioners' butters or hard butters. These have a wide variety of uses, being applied for example as candy couvertures or as biscuit fillings, the fat usually being blended for such purposes with flavouring substances and sugar.
The melting requirements for confectioners' butters are apt to differ somewhat from those which are accepted for fats intended for use in chocolate compositions. For the specialised requirements of hard butters lauric fats are particularly prized. These include coconut oil, palm kernel oil and babassu oils, although there are many others. This class of vegetable fats is so-called on account of their high content of lauric acid, usually in association with myristic acid, which are largely responsible for the desirable melting characteristics for which these fats are preferred.
Lauric fats are however expensive, and attempts have been made to incorporate other, less expensive fats, without rendering the resulting composition unacceptable for hard butter purposes. From the foregoing account however it will be apparent that the parameters governing the extent to which cheaper fats may be incorporated cannot be rationalised for practical purposes in terms of fatty acid composition alone and the art remains one of matching melting requirements with empirical recipes of natural, if modified fats.
2. The Prior Art
The use of interesterification as a method of modifying the melting behaviour of edible fats including lauric fats has been widely disclosed and may be exemplified by reference to U.S. Pat. Nos. 2,442,531 and 2,442,532 (Eckey). In British Pat. No. 955,788 (Canadian Packers) a confectionery coating fat is disclosed consisting essentially of hydrogenated palm kernel oil, part of which only is randomised. The preparation of hard butters based on mixed lauric and non-lauric fats is exemplified in British Pat. No. 1,102,944 (Nestle) in which a blend of short and long chain glycerides is disclosed as a chocolate fat melting at 22.degree.-35.degree. C. and having an iodine value falling within the range 30-35. The latter requirement is a measure of the extent of unsaturation and hence of the complement of unsaturated fatty acids, which contribute to the softness of the product and together with the kinds of fat components used to provide the long chain glycerides, renders the product less suitable for certain purposes as a confectionery fat.
The iodine values which may be calculated from the fat compositions disclosed in British Pat. No. 1,107,207 (National Biscuit Co.) all fall within a range which is too low for the purposes of defining the most suitable confectionery fat. This Patent describes fat compositions prepared by co-randomisation of a saturated fat with a major proportion of a half-hydrogenated lauric fat.
A wide range of hard butter compositions is disclosed in U.S. Pat. No. 2,726,158 (Glidden) in which a fat formulation is described including rearranged blends of lauric and non-lauric fats which are then hydrogenated and conform to specified iodine value and fatty acid chain length ranges. All the Examples with which the disclosure is specifically exemplified however are based on fat compositions whose stearic content and iodine values are too high to afford the most suitable fat blends for confectioners' butter. Similarly the fat compositions disclosed in U.S. Pat. No. 2,936,238 (Weiss) are based on co-randomised lauric and non-lauric fats that all show an iodine value which is too low and/or a stearic acid content which is too high for best results. Again, in U.S. Pat. No. 3,085,882 (Gooding et al) a fully hardened fat contributes, with the palm kernel oil with which it is co-randomised, a stearic acid content that is probably too high in all possible proportions of the components in the product, the iodine value of which is in any event too low for best results in confectioners' fats.
U.S. Pat. No. 3,396,037 (Bell et al) discloses a rearranged fat for use as a hard butter which is characterised by a rapid setting time and is based on a randomised lauric fat optionally hydrogenated and blended with a non-lauric fat or other fatty acid ester intended to supplement for example the stearic acid content of the fat. As with the preceding disclosures however, the Patent fails to emphasise the selection of compositions represented by the stearic acid content and degree of unsaturation which must be met to give the most suitable fat composition for confectioners' butter.
This invention relates to edible fat compositions, more particularly of the kind known as confectioners' butters.
Confectioners' butters are used in fillings for biscuits, candies and chocolate bars. They find widespread use also in cake fillings.
Lauric fats, chiefly coconut, palm kernel, babassu and tucum oils are themselves a valuable source of confectioners' butters, providing in a substantial measure, often after fractionation and/or hardening, the requirements for these products, chiefly sharp melting characteristics over a narrow temperature interval and range from products which are crisp and easily snapped to others which while firm at 20.degree. C. are yet moderately soft to the tooth on biting. They change to a wholly-melted, thin liquid at about 35.degree. C. or slightly above, in the region of body temperature. Their composition chiefly comprises lauric glycerides with varying amounts of other combined fatty acids, particularly myristic acid.
The present invention provides confectioners' butter having iodine value of from 10-25, and the fatty acid composition in random distribution of a blend of a non-lauric fat with a lauric fat, the said composition comprising at least 88 wt % C.sub.10 -C.sub.18 fatty acids including not more than 25 wt % stearic acid. Preferably the stearic acid content is less than 15 wt %. Blends are further preferred which have iodine values of at least 12.
Preferably also the non-lauric fat is steeply-melting and has an iodine value of less than about 20 and a slip melting point of at least 20.degree. C., but particularly at least 35.degree. C. and more especially at least 45.degree. C.
By a steep melting non-lauric fat is meant one having a dilatation drop of at least 500, preferably at least 700 and more particularly 1000, within 10.degree. C. and preferably within 5.degree. C. of the slip melting point of the fat.
The invention includes compositions based on lauric and non-lauric fat fractions, whether obtained by dry fractionation, solvent fractionation or fractionation techniques in which aqueous surfactant solutions are used, in addition to the whole fats. Moreover, the non-lauric fat may be a hydrogenated fat, whether partly or fully hydrogenated, or a stearine thereof.
For the lauric fat component, palm kernel oil is particularly suitable, although babassu, coconut or tucum oil may for example also be used, preferably after removal of a stearine fraction which may itself be a suitable source of confectioners' butter. The invention thus enables increased yields of confectioners' butter to be provided from a lauric fat, by utilising an oleine fraction in addition to the conventional stearine fraction.
A wide range of fats is suitable for providing the non-lauric component of the interesterified blend according to the present invention. Preferably the non-lauric component comprises a C.sub.16 /C.sub.18 vegetable oil, a very suitable source being palm oil. Others include for example oleines from sal fat. The specified requirements for the product, particularly as to iodine value and stearic acid content, must however be met and to this end it may be necessary to modify the fat selected for the non-lauric fat, for example by hydrogenation and fractionation.
The extent to which the lauric or non-lauric components of the interesterified blends according to the invention are first fractionated or the non-lauric component hydrogenated, if at all, may be varied in accordance with the particular requirements for the product, subject to meeting the above-stated characteristics. However, confectioners' butters are characterised by a sharp melting range somewhat below body temperature, reflected in a drop of dilatation values of at least 500, more preferably at least 700 over the last 10.degree. C. below the slip melting point, which should be between 28.degree. and 40.degree. C., preferably between 30.degree. and 37.degree. C. and especially 30.degree.-35.degree. C. Any fractionation and hydrogenation of the components for the interesterified product should therefore be carried out with this end in view. Where the confectioners' butter is intended for use in biscuit creams the D.sub.20 should be below 1500 and preferably below 1100, but preferably at least 900, while its D.sub.30 should be about 300.
A suitable palm oil fraction is provided by the higher melting residue obtained by solvent fractionation of palm oil to obtain a mid-fraction suitable for use as a cocoa butter extender. The mid-fraction obtained under these circumstances has an iodine value of from 25-40, and the stearine fraction has an iodine value of about 5-20, preferably 8-15, and a slip melting point of 50.degree. C. or more, according to the source of the palm oil and the extent to which it is fractionated to obtain the mid-fraction. Other fractionation techniques may however be used, if necessary in conjunction with hydrogenation, to yield a fraction preferably having a slip melting point of at least 45.degree. C. and more preferably at least 50.degree. C. and an iodine value of at most 20, preferably 2-15, for the non-lauric component of the invention. It is usually necessary to hydrogenate dry fractionated palm stearine to achieve a D.sub.20 of at least 500 in the interesterified product.
A suitable source of a palm kernel fraction as the lauric component is the oleine residue remaining after removal of a stearine fraction for confectioners' butter from palm kernel oil, whether by dry, solvent or other fractionation. The oleine fraction thus obtained generally has an iodine value of from 15 to 25.
The proportion of the lauric and non-lauric components of the products of the invention may be varied between wide limits. Preferably however the lauric:non-lauric weight ratio is less than about 5:1, and more preferably the lauric component is the major component in a ratio up to 4:1, especially up to 3:1, to allow the quick melting characteristics of the lauric fat to persist in the blend. The setting point is preferably between 25.degree. and 30.degree. C., preferably about 27.5.degree. C.
The interesterification is carried out in a conventional manner, the fat blend being melted and the reaction carried out in the presence of an effective amount of an interesterification catalyst. This is preferably a hydroxide or lower alkoxide of an alkali metal, preferably sodium, or the alkali metal itself. Sodium methoxide, sodium hydroxide and sodium metal are particularly preferred. Reference may be made for the purpose of carrying out the interesterification to our co-pending Case No. A.267, British Patent Application No. 33362/68. The process may be carried out at temperatures between 15.degree. and 150.degree. C., provided the fat blend is liquid. Preferably however the interesterification is carried out within the range from 50.degree.-100.degree. C., for example 70.degree. C. At such temperatures the reaction is usually completed within an hour. The amount of catalyst used is preferably between 0.01 and 5% by weight, preferably between 0.1 and 1%, for example 0.5%.
Small amounts of additional fat components may be included before or after interesterification, provided these do not markedly influence the sharp melting characteristics of the interesterified blend.
Deodorisation markedly improves the eating qualities of the interesterified blend, but is also useful in removing any volatile components formed during the interesterification, e.g. methyl esters formed by reactions in which sodium methoxide was the catalyst. The presence of such volatile components may lower the dilatation results slightly. The physical properties of an undeodorised product should therefore be used with some caution, as it is those of the fully refined and deodorised product which relate to its performance in an edible composition, and to which therefore reference is made in the text, except where otherwise stated.
In the preparation of biscuit filling creams, coatings and the like, the fat compositions of the invention are usually blended with a suitable sweetening agent, preferably icing sugar, in an amount preferably from 2:3 to 3:2 parts by weight. Other additives or bulking agents may be added to reduce the fat content, e.g. milk powder and whey powder, in addition to flavouring agents, e.g. vanillin, or defatted cocoa powder.
Dilatation values of the non-lauric fat component of the invention may be measured in accordance with the method described in our British Pat. No. 855,349 (Case L.114). Where difficulty is experienced in applying this method, for example to very hard palm oil fractions or other very hard fats whose crystallisation and expansion characteristics may lead to the formation of vacuoles and gas bubbles which invalidate the experiment, or even crack the glass where used, alternative methods for determining the solids content at specified temperatures are shown, including nuclear magnetic resonance, differential thermal analysis and differential scanning calorimetry.
Iodine values referred to in the text are measured according to Wijs' No. 1 method described in British Standard Specification No. 684/1958 on page 74 and slip melting points as described on page 14 of the same reference.
It will be clear to those practised in the art, that where a small reduction in the iodine value of the mixture is desired to satisfy the demands of the final application, this may be achieved by hydrogenating the lauric component, the nonlauric component, or both, or by hydrogenating the blend either before or after interesterification, provided that in each case the final iodine value is within the required range. In general however, where hydrogenation is an expensive process it will be most economic to hydrogenate one of the components, for instance the non-lauric component, instead of the blend. On the other hand, where the colour, taste and shelf-life of the final product are of great importance, it may be of advantage to carry out the hydrogenation after the interesterification.